This invention relates in general to a method of producing gases containing hydrogen and carbon monoxide and in particular to a new and useful process for producing gases containing hydrogen and carbon monoxide from ash oil.
Such ash oils or residual oils rich in ash are obtained in crude oil refining processes. In the coal liquefaction also, an oily suspension of ash containing residual coal is obtained as residue. Both these residual oils are considered as ash oil for purposes of the present invention.
The method of producing process gases containing hydrogen and carbon monoxide from ash oils is similar to the coal gasification method. In the last named method, gas heat in excess is transferred for a large part to indirectly water-cooled, radiated heat absorbing surfaces of a radiant boiler. Ash particles are collected in the water and drained, while the pre-cooled process gas, still carrying ash particles and non-converted carbon, is further cooled, in a convective waste-heat boiler and with steam generation, to 250.degree. to 300.degree. C. and then purified in a scrubber and again cooled.
The reductive and catalytic processes in which the gases are to be used after scrubbing and maybe drying, require pressures of 20 to 60 bar. Accordingly, taking into account pressure losses, the ash oil is gasified in the pressure reactor at pressures of 25 to 80 bar. To control the reaction, steam is fed into the gasification flame. The operating temperatures are in the range between 1,300.degree. and 1,500.degree. C. This is wanted because at such high temperatures a high carbon conversion is obtained and, in addition, the ash particles become plastic and can agglomerate to an easily separable size.
In the prior art method of ash oil gasification, not inconsiderable amounts of non-converted carbon, particularly in the form of carbon black, are entrained by the gas and pass into the wash water. Recovering of this increased carbon proportion in the wash water is indispensible for the economy of the process. It is, therefore, washed out in a benzine scrubber, the carbon enriched benzine is mixed with a part of the ash oil to be introduced, the benzine is stripped off, and the ash oil enriched with fine carbon is fed into the process.
This manner of recovering non-converted carbon requires a considerably expensive equipment for the processing and circulating of the petroleum benzine. In addition, compensation for occurring benzine losses must be provided, so that the method is permanently charged with expenditures.
A method permitting to gasify the ash oil without the expensive benzine scrubbing of the crude process gas would, therefore, be advantageous.